[Elecraft] KEYOUT PTT only when transverter band selected

[Joe Subich, W4TV]

The circuit is called an OR gate - output high if either 
input is high.  The easiest way to homebrew one is to use 
a dual opto-isolator with the outputs in series ... 

The attached assumes DIGOUT will sink a few mA - adjust R 
for the current required by the opto-isolator you use. 

73, 

   ... Joe, W4TV 
 



> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Julian, G4ILO
> Sent: Sunday, July 12, 2009 1:19 PM
> To: elecraft at mailman.qth.net
> Subject: [Elecraft] KEYOUT PTT only when transverter band selected
> 
> 
> 
> I don't have a linear amplifier. I do have a transverter, and 
> I use the KEY OUT jack to put it into TX. Trouble is, it puts 
> the transverter into TX whatever band I'm using. For LO 
> stability reasons (not to mention that I can never remember 
> to switch the transverter off when I'm not using it) I'd 
> prefer to be able to leave the transverter switched on but 
> only receive a PTT signal when the VHF band is selected. I 
> think that means I'd need a circuit that combines the state 
> of DIGOUT0 with KEYOUT-LP, such that it grounds the 
> transverter PTT input when DIGOUT0 is 0V and KEYOUT-LP is 
> grounded. Has anyone made something like that?
> 
> -----
> Julian, G4ILO. K2 #392  K3 #222.
> * G4ILO's Shack - http://www.g4ilo.com
> * KComm - http://www.g4ilo.com/kcomm.html
> * KTune - http://www.g4ilo.com/ktune.html
> 
> -- 
> View this message in context: 
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